1. Field of the Invention
The present invention relates in general to an illuminated indicator gauge, such as speedometer and tachometer used in a motor vehicle or the like, and more particularly to such a gauge having a dial board and a pointer which are illuminated by a light source.
2. Description of the Prior Art
Since many indicator gauges are used in surroundings which receive very little light, either naturally or artificially, various arrangements have been made to illuminate such gauges so that they can be easily read. Such gauges are generally provided with their own light source for the purpose of the above. Many types of gauges are so constructed that light rays from the light source are directed radially from outside of the dial board to illuminate the indicia of the dial board and the position of the indicator pointer.
One of the gauges of such types is shown in FIG. 3 of the accompanying drawings. The gauge comprises a housing 1 which has a base member 7 connected thereto. The movement 2 of the gauge is secured to the base member 7 through bolts 3. A spindle 4 extends forward from the movement 2 and passes through a bore (no numeral) of a dial board 5 which is arranged in front of the movement 2. A pointer 6 is connected to the leading end of the spindle 4, so that the pointer 6 can swingably move over the face of the dial board 5. A transparent cover 9 is fixed to a front open part of the housing 1. On an upper part of the housing 1, there is arranged a light source 8 from which visible light rays are emitted for illumination of the dial board 5 and the pointer 6.
However, due to its inherent construction, the gauge has the following drawback.
That is, because the illumination of the dial board 5 and that of the pointer 6 are equally and entirely made throughout the front surfaces of them, sufficient contrast is not provided therebetween. This will limit the reliability of sure distinction of the pointer 6 from its background that is the face of the dial board 5. This drawback will cause difficulties to arise in clearly and quickly reading the indicia on the dial board 5.